Climate Change GN

Climate and related environmental changes expected

The great majority of the Goldfields – Nullarbor subregion is classified by the CSIRO as “Dry” (where the moisture index & growth index is high in warm season, low in cool season), and “Arid” according to ABARE (2012). However the far south west of the subregion is considered as “Wheatbelt” by ABARE and the agro-climatic zone tends towards a “Mediterranean” classification with a warm climate and a moisture index that is high in winter, low in summer with peak growth in winter and spring (CSIRO, 2008). In this region the most likely impacts of climate change will manifest as:

There will be an increased fire frequency with changed seasonality and intensity

The vegetation structure will gradually change from forest to woodland, to shrubland and grasslands

There is potential for significant landuse changes with conversion of pasture and wetlands to crop

Increased variability will create a climate suiting more opportunists, semi arid and weedy species

There will be a negative impact on wetlands, rivers, and water extraction, dams, groundwater from reduced rainfall and increased evapotranspiration

Projections

Average annual increase in temperature in the range of +1°C to +2°C by 2050

Summer +1°C to +2°C

Autumn +1°C to +1.5°C

Winter +1°C to +1.5°C

Spring +1°C to +2°C

Average annual change in rainfall to decrease by -2 to 10% by 2050

Summer -2% to +5%

Autumn -2% to +5%

Winter -5% to +10%

Spring -5% to +10%

Average annual relative humidity to generally decrease by -0.5% to -2% 2050

Summer -0.5% to -1%

Autumn -0.5% to -1%

Winter -0.5% to -2%

Spring -0.5% to -2%

Annual average wind speed to remain constant through to a 2% increase by 2050

Summer +2 to +5%

Autumn 0% to +5%

Winter -5% to -10%

Spring -2% to +5%

Annual average potential evapotranspiration to increase by +2% to +4% by 2050

Summer +2 %

Autumn +4%

Winter +4% to +8% (with the highest change in the far south west of the subregion)